Only in San Francisco can tech geeks and Hollywood stars so easily co-exist on a red carpet.

Bay Area digerati, like Instagram co-founder Mike Krieger, walked alongside “A Song of Ice and Fire” author George R.R. Martin and “Game of Thrones” stars Kit Harington, Rose Leslie and Nikolaj Coster-Waldau Wednesday night as HBO hosted a screening and Q&A about the returning drama series at San Francisco’s Palace of Fine Arts.

The tech crowd has a particular fascination with “Game of Thrones,” said Craigslist founder and self-proclaimed nerd Craig Newmark, because of the show’s complex mix of history and fantasy.

“We want to live in the future and the past, and this way we get both,” said Newmark, who noted that he first got to know Martin at science fiction conventions in the 1980s. “Seriously, this stuff influences all my work. If you want to build the future, you have to do it using the bones of the past and if you read a lot of fantasy and science fiction, it gives you ideas.”

Following a screening of the third season’s opener — Non-spoiler alert! The episode features gore, nudity and dragons — All Things D head honchos Walt Mossberg and Kara Swisher interviewed Martin and “Game of Thrones” executive producers and showrunners David Benioff and D.B Weiss on stage.

During the session, Martin reassured fans that he was hard at work on the sixth book of his “A Song of Ice and Fire” series, though he’s given up predicting how quickly he’ll finish. He added that he certainly hoped he would be done soon enough for Benioff and Weiss to complete their vision for their adapted series before they retire.

Benioff and Weiss spoke about how this coming season, which debuts on HBO on Sunday March 31, was their most daunting. Not only did they have two full film units shooting simultaneously, but they also shot on five continents and only adapted the first half of “A Storm of Swords,” the novel their season is based upon. Weiss also teased that this season, while certainly darker in tone, also featured more romance (of the non-brothel variety).

“No one wants to be oppressed by their entertainment,” he said.

Given their digital-leaning audience, Benioff and Weiss also praised the way social media has helped the show grow into a cultural phenomenon, while Martin proudly declared himself a Troglodyte who still wrote his novels on a DOS-based computer with WordStar 4.0 and “would still prefer to tie parchment paper to the legs of ravens” than use many of today’s technologies. Martin added that was interested to see how distribution models for film and television would shake out, especially in light of “Game of Thrones” being the most pirated show currently on the Internet. (Australian viewers, Martin’s looking at you.)

Following the Q&A, the tech-heavy crowd was ushered into an adjoining room for a party, where guests could get their picture taken on a replica of the series’ iconic Iron Throne and munch on a variety of meat skewers and the “King’s Landing Midnight Plate” — braised beef short ribs with parsley root puree and first crop spring asparagus.

The San Francisco event was only one of many premieres HBO has planned for the returning show. Following an event in Los Angeles earlier in the week, several members of the cast are next off to Seattle and New York.

“We’re on a proper North American tour,” said Kit Haringon, who plays Night’s Watch soldier Jon Snow. “Because all the actors are predominantly from England, it’s nice to be brought over here in mass and appreciate the fan base over here.”

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Speakeasy is a blog covering media, entertainment, celebrity and the arts. The publication is produced by Barbara Chai and Jonathan Welsh with contributions from the Wall Street Journal staff and others. Write to us at speakeasy@wsj.com or follow us on Twitter at @WSJSpeakeasy or individually @barbarachai.